Traiblazer 2002 overheating [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Traiblazer 2002 overheating


willnavarro
12-01-2008, 06:17 PM
Hello, I have an 02 trailblazer and presents this problem: when I start the engine the fan clutch engages and it blows 100% (a little noisy), then when temperature rise up until 75°C, it desengages until the engine comes overheated (about 120°C) and engages again, but its too late to cool the engine. why is this happening? itīs the thermostat wrong? or the fan clutch?
Besides, I checked coolant level, looked for leakage and everything looks fine, I went to a mechanic and he said that the fan clutch was damage, but I dont believe him because it works, not when I need it, but it engages and disengages.
This occurs when I'm travelling or in hot days.

Michblaze02
12-02-2008, 07:03 PM
Could be the thermostat. Does the check engine light come on at all :undecided. If so might want to have auto zone or someone check the code and to let you know what's causing the issue. Don't think it really has anything to do with the fan though :m2:

willnavarro
12-03-2008, 12:48 PM
thank you man...I think it could be the PCM or coolantīs sensor after check some reviews... No way out, I have to bring it to the dealer :hissy:

cgallo
12-13-2008, 08:37 AM
thank you man...I think it could be the PCM or coolantīs sensor after check some reviews... No way out, I have to bring it to the dealer :hissy:

Hi to All, I think it could be a clogged radiator or the termostat, you can tested with a infrared gun wich measure the temperature, you need to measure in the upper and the bottom of the radiator and you must see the temperatue diference, if not, the termostat could be stucked closed.

cesar gallo

willnavarro
12-13-2008, 02:28 PM
when you say ""you need to measure in the upper and the bottom of the radiator and you must see the temperatue diference" you mean the connecting hoses to the engine system?

cgallo
12-18-2008, 08:57 PM
Exactly, the normal operating temperature is 92 centrigrades in the upper metalic elbow and near of 70 centigrades in the lower elbow.

Cesar


QUOTE=willnavarro;644608]when you say ""you need to measure in the upper and the bottom of the radiator and you must see the temperatue diference" you mean the connecting hoses to the engine system?[/QUOTE]

willnavarro
02-11-2009, 08:53 PM
I changed the thermostat and the water pump... nothing!! :mad: , Im going to check the radiator and the hoses... Somebody help me!!!

the roadie
02-11-2009, 09:05 PM
If it's overheated, and the fan clutch is the problem, the Service Engine Light should be on, and you or your mechanic need to use a scan tool and get the stored error codes. With the codes, we can look them up and confirm if it's the fan clutch or not.

It could also be a clogged radiator, as mentioned before. Do you have somebody who knows how to troubleshoot cooling problems? If not, you will be throwing parts at this problem until you run out of money.

I don't think you ever replied to the question from 12/2 about the check engine light, or codes.

The vehicle is very smart about diagnosing problems itself, but you have to talk its language to have an intelligent conversation.

willnavarro
02-12-2009, 01:11 PM
The light never turns on, I tried the sensor disconnecting the fan clutch and then is when the light turns on, but after I plug in the connector it turns off. I think it isnīt the fan clutch but I really donīt know

Super 88
02-12-2009, 01:41 PM
Hello, I have an 02 trailblazer and presents this problem: when I start the engine the fan clutch engages and it blows 100% (a little noisy), then when temperature rise up until 75°C, it desengages until the engine comes overheated (about 120°C) and engages again, but its too late to cool the engine. why is this happening? itīs the thermostat wrong? or the fan clutch?
Besides, I checked coolant level, looked for leakage and everything looks fine, I went to a mechanic and he said that the fan clutch was damage, but I dont believe him because it works, not when I need it, but it engages and disengages.
This occurs when I'm travelling or in hot days.

You people that use C for your temperature! It's confusing for us F. people. :D (Just joking)

So let me get this straight. When you start the engine cold, the fan clutch engages and stays engaged until 75C which is about 167F. When you say engaged do you mean that the fan clutch is 100 percent engaged, in other words a loud roar?
If so that right there means the fan clutch is bad. They sometimes roar for a few seconds when you start the engine, but it shouldn't for that long.

120C = 248F which is a little on the hot side for these engines. Roadie can give you exact numbers, but at around 200 degrees the fan should be spinning slowly, and increase in rpms the higher you go temperature wise. At your high temp of 120C I would think that fan clutch should be roaring - or close to it.

I don't understand why you don't believe your mechanic. This is not meant to be mean, but it's possible he knows a little more about these things than you do.

You said you changed the water pump and the thermostat. Okay that didn't help.
There are only 3 other possibilities.
First one is the radiator. Maybe, but I'd guess on no. 2

Second - of course the fan clutch. I'd say highly likely.

Third - a head gasket problem. If you blow a head gasket sometimes the exhaust will "leak" into the coolant and make the engine overheat or run very hot.

sctb
02-12-2009, 07:39 PM
My clutch never gave a CEL, and the dealer said it was bad. Hmmm. It engaged and disengaged, but along with the obviously bad water pump bearings, they said it was not running like it should.

What are the chances the ECT sensor is bad and giving a false reading? Would that set a code or not?

Thermostat fixed mine ultimately, but he has changed that.

the roadie
02-12-2009, 08:08 PM
My clutch never gave a CEL, and the dealer said it was bad. Hmmm. It engaged and disengaged, but along with the obviously bad water pump bearings, they said it was not running like it should.Nonsense and balderdash, I say to the dealer who would lie like that. The fan clutch has an input command signal and an RPM output sensor signal. If the fan is spinning SLOWER than commanded, it sets one kind of code. If it's spinning FASTER than commanded, it sets another kind of code. I can see no other situation. The fan is either spinning faster, slower, or just right.
What are the chances the ECT sensor is bad and giving a false reading? Would that set a code or not?It would set a code if the sensor wiring was broken or shorted to ground, or the sensor failed at full scale high or low. The PCM has no way of telling if a bad sensor is a little bit off, though. There's no sensor redundancy (as there is on the throttle pedal position), but if you watch the gauge and it looks like it's reading 180 when it should be 210 and you know your thermostat is good, then you can suspect an inaccurate sensor.

The code for a bad sensor will be set if it gets a reading that implies a coolant temp of below -38 F or above 280 F for more than six seconds.

Super 88
02-12-2009, 08:20 PM
Nonsense and balderdash, I say to the dealer who would lie like that. The fan clutch has an input command signal and an RPM output sensor signal. If the fan is spinning SLOWER than commanded, it sets one kind of code. If it's spinning FASTER than commanded, it sets another kind of code. I can see no other situation. The fan is either spinning faster, slower, or just right.It would set a code if the sensor wiring was broken or shorted to ground, or the sensor failed at full scale high or low.

I hear what you are saying Roadie, but when I had my fan clutch replaced there was no CEL and no codes.

My problem was the a/c didn't work well at low speeds in high temps. Classic case - my wife and I were over in Riverside for our anniversary (in August) and unless we were driving on the freeway, I was getting 90 degree air out of the vents (the ambient temp. was about 95 - 100).

The dealer (in San Diego) checked the a/c system, said nothing is wrong. It was blowing 40 degree air - in San Diego on a cool morning when the ambient temp was under 70 degrees.

I showed them the TSB about poor cooling at low speeds and they called me back about 4 hours later and said we replaced your fan clutch you are good to go.
Now the a/c blows ice cold sitting idling at any ambient temp.
But I never had any trouble with overheating, and the fan clutch did not stay engaged either. IDK!

the roadie
02-12-2009, 08:29 PM
I hear what you are saying Roadie, but when I had my fan clutch replaced there was no CEL and no codes.

My problem was the a/c didn't work well at low speeds in high temps. Classic case - my wife and I were over in Riverside for our anniversary (in August) and unless we were driving on the freeway, I was getting 90 degree air out of the vents (the ambient temp. was about 95 - 100).
Interesting. The TSB had two parts (new clutch and a reflash), and I bet reflashing the PCM to give the fan clutch more high speed time at initial start-up when the coolant temp was low (or you're at idle with high ambient) was the bulk of the fix.

I had the same problem, and before they came up with the reflash, I had been in twice for poor AC performance. Finally, just before the warranty was up, the clutch died and I got a free one. Better AC performance was an accidental side effect of that visit.

If only we had a report from somebody whose dealer ONLY did the reflash and didn't change the clutch, we could know for sure. Or from a GM insider who knows the truth.

Super 88
02-12-2009, 08:38 PM
Interesting. The TSB had two parts (new clutch and a reflash), and I bet reflashing the PCM to give the fan clutch more high speed time at initial start-up when the coolant temp was low (or you're at idle with high ambient) was the bulk of the fix.

I had the same problem, and before they came up with the reflash, I had been in twice for poor AC performance. Finally, just before the warranty was up, the clutch died and I got a free one. Better AC performance was an accidental side effect of that visit.

If only we had a report from somebody whose dealer ONLY did the reflash and didn't change the clutch, we could know for sure. Or from a GM insider who knows the truth.

FWIW, I found the TSB, and according to it only the 2004 and earlier models needed the PCM reflashed, but vehicles built before June 2005 needed the new model clutch (mine was Nov. 2004).
http://forums.trailvoy.com/showpost.php?p=408562&postcount=246

Yes, it would be interesting to hear from a GM insider. Where can we find one? :D

Sadly now - but at the time I wasn't too concerned about which it was (PCM reflash or new fan clutch). I just wanted my new 33K vehicle to cool better or at least as good as my old vehicles!

Robert1101
02-12-2009, 10:42 PM
Interesting. The TSB had two parts (new clutch and a reflash), and I bet reflashing the PCM to give the fan clutch more high speed time at initial start-up when the coolant temp was low (or you're at idle with high ambient) was the bulk of the fix.

I had the same problem, and before they came up with the reflash, I had been in twice for poor AC performance. Finally, just before the warranty was up, the clutch died and I got a free one. Better AC performance was an accidental side effect of that visit.

If only we had a report from somebody whose dealer ONLY did the reflash and didn't change the clutch, we could know for sure. Or from a GM insider who knows the truth.

I did not like the cooling of mine in traffic so I paid for the reflash and all updates prior to my PCM tune. I have the orig. clutch and it is a lot cooler in traffic now and my wife is much happerier.

sctb
02-12-2009, 10:51 PM
What wisdom there is to be found in GM!! I have an 05, so apparently I had the new software but the old style fan clutch.

I can hear the meeting now..."Hey, here's a thought. Let's update the software because we know there's a problem, but let's not fix the real problem, but only create other problems to distract everyone from the problem. And let's put the software to fix the problem hardware out there before we have the new hardware installed. And let's be sure to charge out the wazoo for the problem. Any problems?" :undecided

I tried the approach with GM that there were 2 updates to the fan clutch and software updates as well to try and get some price relief. No luck.

willnavarro
02-13-2009, 01:54 PM
You people that use C for your temperature! It's confusing for us F. people. :D (Just joking)

So let me get this straight. When you start the engine cold, the fan clutch engages and stays engaged until 75C which is about 167F. When you say engaged do you mean that the fan clutch is 100 percent engaged, in other words a loud roar?
If so that right there means the fan clutch is bad. They sometimes roar for a few seconds when you start the engine, but it shouldn't for that long.

120C = 248F which is a little on the hot side for these engines. Roadie can give you exact numbers, but at around 200 degrees the fan should be spinning slowly, and increase in rpms the higher you go temperature wise. At your high temp of 120C I would think that fan clutch should be roaring - or close to it.

I don't understand why you don't believe your mechanic. This is not meant to be mean, but it's possible he knows a little more about these things than you do.

You said you changed the water pump and the thermostat. Okay that didn't help.
There are only 3 other possibilities.
First one is the radiator. Maybe, but I'd guess on no. 2

Second - of course the fan clutch. I'd say highly likely.

Third - a problem. If you blow a head gasket sometimes the exhaust will "leak" into the coolant and make the engine overheat or run very hot.


How could I Know if the head gasket is damage?

My TB is 2002 could be a problem with the PCM? It is possible to change the fan clutch rpm to blow faster when its iddle?

I ask because When I go in the freeway the temperature seems to be normal, but right after I get out of it, If I find traffic jam temperature rise up.

Super 88
02-13-2009, 03:56 PM
How could I Know if the head gasket is damage?

My TB is 2002 could be a problem with the PCM? It is possible to change the fan clutch rpm to blow faster when its iddle?

I ask because When I go in the freeway the temperature seems to be normal, but right after I get out of it, If I find traffic jam temperature rise up.

That sure sounds like the fan clutch. At freeway speeds you have enough air blowing over the radiator to cool everything. In traffic you need the fan spinning to bring air in to cool the radiator.

As Roadie and Robert1101 mentioned -the dealer has a update to the PCM which will command the fan to spin a little faster at lower RPMS. Also from what I remember the new fan clutch part number was changed to move more air at lower speeds.
This isn't free either - IIRC people have said in the neighborhood of 100.00 or so.

If the head gasket was damaged, it would run hot ALL the time, and overheat VERY quickly. I've seen a few cars (non Trailblazers) with this problem, and they will start overheating literally in a matter of minutes.
Also - often when you have a bad headgasket you will have white smoke blowing out your exhaust pipe with what some call a "sweet" smell. I always thought it just smelled like burnt anti-freeze!
I don't think you have a head gasket problem.

I've said it before, I'll say it again - I think you have a bad fan clutch.

If you go to the dealer for the fan clutch it is expensive. 500 or 600 bucks comes to mind.
If you look around I think we have seen the OEM clutches from various sources for about 170 - 200.00 They aren't cheap. I would go with the OEM or from the maker of the OEM and MAKE SURE it's the latest part number. I don't have the part number in front of me - but it's been mentioned on this forum NUMEROUS times. Do a search for latest fan clutch number or something like that.

willnavarro
02-13-2009, 09:48 PM
That sure sounds like the fan clutch. At freeway speeds you have enough air blowing over the radiator to cool everything. In traffic you need the fan spinning to bring air in to cool the radiator.

As Roadie and Robert1101 mentioned -the dealer has a update to the PCM which will command the fan to spin a little faster at lower RPMS. Also from what I remember the new fan clutch part number was changed to move more air at lower speeds.
This isn't free either - IIRC people have said in the neighborhood of 100.00 or so.

If the head gasket was damaged, it would run hot ALL the time, and overheat VERY quickly. I've seen a few cars (non Trailblazers) with this problem, and they will start overheating literally in a matter of minutes.
Also - often when you have a bad headgasket you will have white smoke blowing out your exhaust pipe with what some call a "sweet" smell. I always thought it just smelled like burnt anti-freeze!
I don't think you have a head gasket problem.

I've said it before, I'll say it again - I think you have a bad fan clutch.

If you go to the dealer for the fan clutch it is expensive. 500 or 600 bucks comes to mind.
If you look around I think we have seen the OEM clutches from various sources for about 170 - 200.00 They aren't cheap. I would go with the OEM or from the maker of the OEM and MAKE SURE it's the latest part number. I don't have the part number in front of me - but it's been mentioned on this forum NUMEROUS times. Do a search for latest fan clutch number or something like that.

thank you man!!!, I'm going to change it.

sctb
02-14-2009, 02:33 AM
thank you man!!!, I'm going to change it.

:iagree: with Super88. The new fan clutch part # is 25790869 (AC Delco) and the dealer charged me $520.97 to replace it. Apparently I already had the software update. Suggestion...buy the clutch and either do it yourself if you feel comfortable doing that kind of thing, or take it to a trusted shop and have them put it in. You'll save a couple of hundred. Check ebay for the clutch. By some miracle, I won one for $30 a year or so ago. Wish I had it back!

Another way to diagnose head gasket is pull the oil dipstick and see if it looks milky. If so, your coolant is getting into the oil. Haven't seen that often if any around here, though.

willnavarro
03-19-2009, 03:11 PM
Last week I changed the fan clutch and the overhating came again, can somebody tell me what to do next?, is it necessary to reset the PCM?? :confused:

the roadie
03-19-2009, 03:22 PM
It should not be necessary to do any reset. Seems you now need a professional mechanic. If it's a head gasket or something worse, that's beyond our capability to help you with on the Internet. It couls also be a clogged radiator, and a good infrared thermometer used by a mechanic should be able to diagnose that.

Super 88
03-19-2009, 03:46 PM
It should not be necessary to do any reset. Seems you now need a professional mechanic. If it's a head gasket or something worse, that's beyond our capability to help you with on the Internet. It couls also be a clogged radiator, and a good infrared thermometer used by a mechanic should be able to diagnose that.

:iagree:
It could be a clogged radiator. But my experience with bad radiators is that the vehicle usually overheats ALL the time - sometimes even worse when driving at higher speeds.

But Roadie is right. It's time to call in the professionals - be it dealership or otherwise.

BTW, has anyone ever checked the condition of the radiator hoses? I've seen old hoses collapse when they get hot and not allow enough antifreeze to circulate.

You really have only about 3 things left.

1. As mentioned plugged radiator.

2. Bad headgasket/cracked head or block.

3. Bad parts already replaced - i.e. thermostat or fan clutch. It's not likely but it is possible.

4. One more - bad sensor. This is were someone with the proper test equipment would be able to see what is really happening.

Sorry we couldn't find your problem. That's the thing about a forum like this - we take our best guess based on our past experience and the input that you give us. Most of the time we are right, but not always!:(

Good luck, let us know what happens.

willnavarro
05-28-2009, 05:17 PM
Finally I know what is wrong, the head gasket, I've tried last week to change it, but several bolts cracked at the block, I already took off 7 but there is one stuck. This weekend Im going to remove the block to take it to the grinder :mad:

Super 88
05-28-2009, 10:39 PM
Finally I know what is wrong, the head gasket, I've tried last week to change it, but several bolts cracked at the block, I already took off 7 but there is one stuck. This weekend Im going to remove the block to take it to the grinder :mad:

Sorry to hear about your problems. Just wondering how you came to the conclusion that the head gasket was bad? I'm not for a second disagreeing, just asking for future reference for others! Thanks!

willnavarro
06-03-2009, 09:13 PM
[QUOTE=Super 88;750435]Sorry to hear about your problems. Just wondering how you came to the conclusion that the head gasket was bad? I'm not for a second disagreeing, just asking for future reference for others! Thanks![/QUO


Take off the radiator cap then start the engine, if the coolant splash your head gasket is blown. Besides, there are oil spots in the cap and hoses.

willnavarro
06-11-2009, 02:57 PM
I already change the gasket, but now i have a new problem, the mechanic who helped me erased the marks I made in the sprockets and timing chain, now I cant put it in time again. I found a manual that says there are dark links in the chain that must be align with the sprokets but in my chain there arent dark links. I try to put the cams with the flats up and check the first piston at the top end, besides checked the exhaust cam actuator and it is fully advance. I dont know what to do!. Can Anybody help me?

davesext
07-05-2009, 06:36 PM
Being here in Houston, this week alone it's been above 100 degrees everyday. My EXT has been above the 210 mark right out of the gate. I read somewhere, possibly here that the dealer has to upgrade the computer for climate. I purchased the truck new in 2002 on the East coast and drover her here to Texas. She's had new hoses, belts, t-stat and coolant added this year prior to the 100 degree temps, and it's not even Summer. We're expecting much hotter days. I'm parking her in the garage for the remainder of the summer till Government Motors gets it act straight. Using ol' reliable, the ever failing 04 Jeep Liberty I got for a song at auction. I replaced the passenger, driver and right rear window regulators in the past two years. What's up with the car makers, they don't want to take responsiblity for design flaws? I bought two regulators from the dealer until I read about the problem and then bought an aftermarket regulator online. It's faster, quieter and seems to be stronger built than the plastic one they gave me at the dealer. ANYWAY. If anyone has read further about this overheating problem let me know. I know there is a viscous clutch that is REALLY expensive. I had one replaced under warranty like six years ago. She's got 125,000 miles on her and she's doing great! I'm gonna give her up though for an Traverse this year. I'm going to link a Traverse, Acadia and Enclave site soon! Just Kidding.

the roadie
07-06-2009, 12:26 AM
...She's got 125,000 miles on her and she's doing great! .I really don't know what to make of your rant, that concludes with "she's doing great".

Please start your own thread instead of hijacking another one, but electro-viscous fan clutches are available in the aftermarket for $150-200; you might need one depending on what a scan tool says about its performance. There was a PCM software update in 2005 that improved AC performance at idle in traffic. ALL of these issues have been extensively discussed, and you can share that by running a search and catching up. THEN start a new thread if you have unanswered questions. Welcome!

roldao
06-19-2011, 02:16 PM
When my TB 2002 started overheating (125 + celsius) I read almost all the forums that convinced me that the Fan Clutch was the cause (Perfect Engine Pressure, No Leaks, Coolant flowing). I had the vehicle checked at several places who told me nothings wrong. I was on the verge of purchasing the Fan clutch from dealer when I decided let the dealer have a look, though expensive. It turns out the Radiator Cap was losing pressure. The radiator has to run at 15PSI. After changing the Cap, TB runs at normal temp ranges (Weird but worked :o ). 100 to 108 celsius. I still need to get the radiator cleaned. In Qatar we are talking about above 50 celsius during summers.

So guys before you go spending big bucks check the simple things.